Analysis
Beforeafter_AVR_system

Adaptive profiling of leading and trailing edges of gas turbine airfoil

AV&R Aerospace’s goal, as it works with its customers, is to be the leader in industrial automation for the aerospace and energy industries by offering intelligent automation solutions to optimise manufacturing processes and to control quality. As it delivers critical solutions, the company has developed a broad range of expertise enabling robots to perform complex tasks that traditionally could be performed only by humans. This allows their customers to achieve high process repeatability and lower cost while enhancing precision in such finishing operations as deburring, polishing, profiling, blending, grinding, buffing and trimming.

The company differentiates itself by providing highly engineered solutions that integrate in depth knowledge of the machining process for optimized tool and abrasive selection and of sophisticated robot control based on inspection feedback. Customers have turned to AV&R Aerospace because; it delivers not only a workcell, but an integrated manufacturing process from the simplest to the most complex of machined parts.

In the aerospace and energy industries, AV&R Aerospace’s expertise have been leveraged in projects for the manufacturing of critical gas turbine rotating parts for both new make and repair.

Context

Fuel consumption for commercial aircraft represents a tremendous expense to airlines and moreover the U.S. Energy Information Administration (EIA) expects jet fuel prices to increase steadily from 2011 onward.

This reality has pushed the engine manufacturers to increase fuel efficiency. To do so, they improved aerodynamics on blades & vanes by using tighter tolerances and more complex elliptical 3D profile. Tolerances on newer engines are around ± 0.0015 in (37 μm) and are planned to go to ± 0.001 in (25 μm). With these new requirements manual profiling is no longer sustainable. Aspects such as labour cost reduction, difficulty to find skilled operator and to eliminate injury have also push to automate this operation. On the repair side, in addition of fuel saving, better aerodynamic leads also to less scrap and longer blade life.

Solution

To answer the gas turbine manufacturers’ needs, AV&R Aerospace has worked closely with their customers to develop an automated profiling system which creates high precision elliptical profiles on blades and vanes according to the new engine design requirements. This 6 axis system integrates adaptive and closed-loop capabilities coupled with leading and trailing edge profile inspection to reach a ± 1.5 thousandth of an inch (± 37.5 μm) tolerance. In addition, the system can polish the blade’s foil, platform and fillet. When adapting the solution for MRO requirements weld blend capabilities has been included for repaired blades that have material added.

One of the largest challenges manufacturing engineers face with automating typically manual processes is being able to handle in-process variations associated with the parts and the process parameters. Therefore to ensure the solution would be sustainable over time and slight manufacturing variations it compensates for leading and trailing edge morphology and positioning variations. To deal with process variations themselves the system compensates for abrasive wear and corresponding changes in material removal rates. Combining all these factors together the machining program is adjusted in real-time for each part being profiled.

To be able to meet customers’ tolerances and reduce time required to introduce new parts in production, AV&R Aerospace has developed an automated method to create the machining program recipe. Instead of creating the machining program with CAD-CAM software, AV&R Aerospace’s automatic teaching software analyses the theoretical 3D models before and after profiling and with artificial intelligence and algorithms creates the machining program. Since 3D models are not exactly as the real part, a laser inspection system analyses the profile quality and if it’s required, automatically adjusts the machining program. With this technology their customers can put the 3D models with 5 to 10 parts in the system to automatically learn a new part.

Confirm results

Today customers, including most of the major OEM engine manufacturers and their suppliers, use AV&R Aerospace profiling and polishing systems to improve aerodynamic performance and reduce labour cost. Systems have been deployed on 4 continents for both new make and MRO facilities. As AV&R Aerospace continues to work with their customers the solution is being expanded from compressor blades and vanes to high pressure turbine blades and fan blades. The goal is to work with any customer who has edges with tight profiles tolerances or surfaces requiring precision finishing.

These technologies have brought the following advantages to the end users:

• Fuel burn reduction
• Performance improvement (maximum profile tolerances ± 0.0015 in (37 μm), average profile tolerance less than ± 0.001 in (25 μm))
• Compensate for production variations
• Airfoils life improvement
• High precision and repeatability
• Scrap rate reduction
• Labour cost reduction
• No need to highly skill labour
• Eliminate injuries
• Eliminate some inspection operations
• Consumable reduction (abrasive wheel, sand belts)
• Short time to put new part in production

AV&R Aerospace’s profiling system won the Society of Manufacturing Engineers’ 2012 Innovations That Could Change the Way You Manufacture Award.

François Arrien, AV&R Aerospace
[email protected]

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